#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	double sum = 0.0;
	int i = 0;
	int sign = 1;
	for (i = 1;i <= 100;i++)
	{
		sum += sign / (double)i;
		sign = -sign;
	}
	printf("%If", sum);
	return 0;
}